JP2013167668A - Developing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a developing device that changes the roughness of the surface of an elastic body of a toner layer regulating blade from the upstream side to the downstream side relative to a direction of rotation of a developing roller so as to ensure conveyability of toner, and includes the toner layer regulating blade that makes a toner layer formed on the developing roller uniform.SOLUTION: In a developing device 1, the roughness of the surface of a rubber-made member 9b of a toner layer regulating blade 9 that contacts a developing roller 6 is changed relative to a direction of rotation R1 of the developing roller 6 from the central point K of blade linear pressure of the toner layer regulating blade 9 with the upstream side U being a rough surface and the downstream side D being a mirror surface. Accordingly, conveyability of toner can be ensured, and a toner layer formed on the developing roller 6 can be made uniform.

Description

  The present invention relates to a developing device used for a copying machine, a printer, a facsimile, and the like.

  Conventionally, in an electrophotographic image forming apparatus, a surface on a photosensitive drum (electrostatic latent image carrier) is charged, and an electrostatic latent image is formed by developing a charged area according to image information, and developing. A method of visualizing (developing) an electrostatic latent image using an agent is employed.

  In a developing apparatus for developing, a non-magnetic one-component developing method using a non-magnetic toner that does not contain a magnetic component such as magnetic powder, a two-component developing method comprising a non-magnetic toner and a magnetic carrier, and containing magnetic powder There is a magnetic one-component developing system using a magnetic one-component toner whose main component is magnetic toner.

  The two-component development method is excellent in electrophotographic characteristics such as transferability, fixing property and environmental resistance. However, since a two-component developer composed of toner and carrier is used, the mixing ratio thereof is controlled by a toner density sensor or the like. In addition, since the agitation function is complicated, the developing device tends to be large and costly.

  On the other hand, the one-component development method does not require a toner concentration sensor and has a simple stirring function, and thus can be reduced in size and cost.

  Further, in the developing method using non-magnetic one-component toner, the toner is held on the developer carrying member (developing roller) only by electrostatic force and mechanical force, so that the adhesion force of the toner on the developer carrying member is high. The toner is weakened and toner is likely to slip through, and image quality may be deteriorated due to toner scattering, and contamination may occur in an image forming apparatus including a developing device.

  For this reason, in the developing device, it is required that the toner layer formed on the developer carrying member is composed of one to three layers that are extremely thin so that excessive toner does not adhere to the developer carrying member. In order to form an extremely thin toner layer, there is a method of increasing the contact force (pressing force) of the developer layer thickness regulating member (toner layer regulating blade) that contacts the developer carrier. In some cases, the driving torque of the developing roller increases to promote toner deterioration, wear of the toner layer regulating blade, and the like.

  In Patent Document 1, the toner layer regulating blade includes an elastic body, and the surface of the elastic body that contacts the toner is a mirror surface, and the other surface is a non-mirror surface. There has been proposed a technique for preventing toner scattering by accelerating the charge diffused to the surface by non-mirror surface irregularities.

Japanese Patent Laid-Open No. 10-104942

  However, in the technique disclosed in Patent Document 1, when the toner is triboelectrically charged at the mirror surface portion of the elastic body, the charging ability is insufficient, and the unevenness of the non-mirror surface portion is low due to scattering because the specific surface area becomes large. There is a problem that it is easy to collect charged toner and toner is easily dropped.

  The present invention has been made in view of the above circumstances, and the surface roughness of the elastic body of the toner layer regulating blade changes from the upstream side to the downstream side with respect to the rotation direction of the developing roller. In particular, it is possible to provide a developing device including a toner layer regulating blade that can ensure toner transportability by providing a rough surface on the upstream side and a mirror surface on the downstream side, and makes the toner layer formed on the developing roller uniform. It is for the purpose.

  In order to solve the above-described problems, each configuration of the developing device according to the present invention is as follows.

  The developing device of the present invention is provided in an image forming apparatus used for image formation, and supplies the developer to the electrostatic latent image formed on the electrostatic latent image carrier, and develops the developer carrier. A developer layer thickness regulating member that regulates the layer thickness of the developer carried on the surface of the developer carrying body, and developing the electrostatic latent image with the developer, wherein the development The agent layer thickness regulating member includes an elastic body that contacts the surface of the developer carrier, and the surface of the elastic body is a surface from the upstream side toward the downstream side with respect to the rotation direction of the developer carrier. Roughness changes.

  The developing device of the present invention is characterized in that, on the surface of the elastic body of the developer layer thickness regulating member, the surface roughness on the downstream side is smaller than the surface roughness on the upstream side. is there.

  Further, in the developing device of the present invention, the surface of the elastic body downstream from the center point of the blade linear pressure of the developer layer thickness regulating member with respect to the rotation direction of the developer carrier is a mirror surface, and the blade The surface of the elastic body on the upstream side with respect to the rotation direction of the developer carrying member from the center point of the linear pressure is a rough surface.

  According to the present invention, the developing device is provided in an image forming apparatus used for image formation, and a developer carrying member that supplies the developer to the electrostatic latent image formed on the electrostatic latent image carrying member and develops the developer carrying member. A developer layer thickness regulating member that regulates the layer thickness of the developer carried on the surface of the developer carrying body, and developing the electrostatic latent image with the developer. The developer layer thickness regulating member includes an elastic body that comes into contact with the surface of the developer carrier, and the surface of the elastic body extends from the upstream side to the downstream side with respect to the rotation direction of the developer carrier. By changing the surface roughness toward the surface, it is possible to secure the toner transportability, to make the toner layer formed on the developing roller uniform, and to improve the fluidity accompanying the deterioration of the toner over a long period of time. Even if toner drops and toner aggregates occur, a uniform toner on the developing roller It is possible to form a layer, an excellent effect of being able to provide a high-quality image.

  According to the present invention, in the developing device, on the surface of the elastic body of the developer layer thickness regulating member, the surface roughness on the downstream side is denser than the surface roughness on the upstream side. Therefore, it is possible to achieve an excellent effect that the toner layer formed on the developing roller can be made uniform.

  According to the present invention, in the developing device, the surface of the elastic body on the downstream side with respect to the rotation direction of the developer carrying member from the center point of the blade linear pressure of the developer layer thickness regulating member is a mirror surface, The surface of the elastic body on the upstream side with respect to the rotation direction of the developer carrying member from the center point of the blade linear pressure is formed of a rough surface to ensure toner transportability and is formed on the developing roller. The toner layer can be made uniform, and a uniform toner layer can be formed on the developing roller even when the fluidity is lowered due to the deterioration of the toner and the toner aggregates are generated over a long period of time. It is possible to provide an excellent effect that a high-quality image can be provided.

1 is a block diagram illustrating a configuration of an image forming apparatus including a developing device according to an embodiment. 1 is a schematic diagram illustrating a configuration of a developing device according to the present embodiment. It is the schematic which shows the structure of the developer layer thickness control member of the image development apparatus which concerns on this embodiment.

  A characteristic configuration of the image forming apparatus 100 including the developing device 1 according to the present embodiment will be described with reference to FIG. FIG. 1 is a block diagram illustrating an electrical configuration of an image forming apparatus 100 including a developing device 1 according to the present embodiment.

  As shown in FIG. 1, the image forming apparatus 100 has, as an electrical configuration, a control unit 201 that controls the operation of the image forming apparatus 100, a storage unit (storage unit) 202, and a determination unit (determination unit) (not shown). A display unit 204, an input unit 205, a communication unit 206 that performs LAN connection with a PC or the like via a network line, an image processing unit 208 that performs image processing, an image forming unit 209 that performs image formation, and a toner image fixing process. A fixing unit 210 to perform, a reading unit 207 to read an image in the scanner, a control unit 211 to control the operation of the image forming apparatus 100, and the like are provided.

  The control unit 201 is connected to the storage unit 202, the display unit 204, the input unit 205, the communication unit 206, the reading unit 207, the image processing unit 208, the image forming unit 209, and the fixing unit 210, respectively. Control.

  The storage medium for storing the program executed by the control unit 201 is not limited to a memory card, and may be a medium such as a flexible memory, an optical disk, an IC card, an optical card, a mask ROM, an EEPROM, or other semiconductor memory. .

  The communication unit 206 transmits / receives data to / from a connected external device in accordance with an instruction from the control unit 201.

  The reading unit 207 includes a light source that irradiates light to the original conveyed to the original reading position and a photoelectric conversion element that receives light reflected by the original, and scans an original image according to the size of the original. The photoelectric conversion element converts the received light into image data that is an electrical signal and outputs the image data to the image processing unit 208.

  The image processing unit 208 performs various data processing such as shading correction on the image data input from the reading unit 207, and then outputs the data to the image forming unit 209. A paper feeding unit (not shown) conveys paper stored in a paper feeding cassette (not shown) and a manual paper feeding cassette (not shown) to the image forming unit 209.

  The image forming unit 209 forms an image on a sheet conveyed by a sheet feeding unit (not shown) based on the image data after data processing. Then, the image forming unit 209 discharges the paper on which the image has been formed onto a paper discharge tray (not shown).

  The fixing unit 210 melts and fixes the toner image formed on the paper by the image forming unit 209 to the paper.

  The display unit 204 uses a liquid crystal display (LCD), an organic ELD (Electro Luminescence Display), a display such as electronic paper using electrophoresis, a plasma display (PDP), a plasma tube array display (PTAD), and an electron-emitting device. A display device such as a display (FED, SED) or the like, which displays an instruction menu such as a setting screen for the user and a screen including information on acquired image data.

  The input unit 205 includes a plurality of keys, and accepts input of various instructions, data such as characters and numbers by user operations corresponding to the keys.

  Next, the developing device 1 according to the present embodiment will be described. FIG. 2 is a schematic diagram of a configuration of the developing device 1 according to the present embodiment.

  The developing device 1 is a non-magnetic one-component developing device that develops an electrostatic latent image by supplying a one-component developer containing only toner to the electrostatic latent image on the surface of the photosensitive drum 2. The developing device 1 includes a developing tank 5, a developing roller 6, a supply roller 7, a stirring member 8, a toner layer regulating blade 9 (developer layer thickness regulating member), a driving unit (not shown), and a power source (not shown). And control means (not shown). The developing device 1 is used in an electrophotographic image forming apparatus 100 including a photosensitive drum 2 for forming a toner image.

  Here, the photosensitive drum 2 is rotatably supported by a support member (not shown), is rotatably provided around an axis by a drive means (not shown), and a photosensitive drum on which an electrostatic latent image and thus a toner image is formed. A roller-shaped member having a film. For the photosensitive drum 2, for example, a roller-shaped member including a conductive substrate (not shown) and a photosensitive film (not shown) formed on the surface of the conductive substrate is used. In this embodiment, an organic photosensitive film is used as the photosensitive drum 2, and the diameter is set to 30 mm, the length is set to 30 cm, and the rotation speed is set to 150 mm / sec. The surface potential of the photosensitive drum 2 was set to -550v.

  The developing tank 5 is a container-like member having a space inside, and contains a developer in the internal space. The developer is a one-component developer containing toner. Further, the developing tank 5 accommodates the developing roller 6, the supply roller 7, and the stirring member 8 so as to rotatably support each of them, and supports the toner layer regulating blade 9.

  Further, an opening (not shown) is formed on a side surface of the developing tank 5 facing the photosensitive drum 2. A part of the developing roller 6 protrudes from the opening toward the outside of the developing tank 5 and is placed in contact with the photosensitive drum 2. A toner cartridge and a toner hopper (not shown) are provided above the developing tank wall in the vertical direction.

  More specifically, the toner cartridge, the toner hopper, and the developing tank 5 are provided in this order from the top to the bottom in the vertical direction. The toner cartridge is a cylindrical container member that stores toner in an internal space, and is detachably attached to the main body of the image forming apparatus 100 provided with the developing device 1.

  Further, the toner cartridge is driven to rotate about the axis by a driving unit (not shown) provided in the image forming apparatus 100. An elongated opening extending in the longitudinal direction is formed on the side surface in the longitudinal direction of the toner cartridge, and the toner falls from the elongated opening and is supplied to the toner hopper as the toner cartridge rotates. The rotation of the toner cartridge is controlled according to the toner consumption status by a control unit (not shown) provided in the image forming apparatus.

  For example, the toner hopper is provided such that a toner replenishing port, which is an opening formed on the bottom surface in the vertical direction, communicates with a toner receiving port, which is an opening formed on the top surface in the vertical direction of the developing tank 5, in the vertical direction. The toner hopper replenishes the developing tank 5 with toner supplied from the toner cartridge. The developing tank 5 is formed of, for example, a synthetic resin, preferably a thermoplastic resin that can be injection-molded.

  The developing roller 6 is a roller member provided so as to be rotatable around an axis by a driving unit (not shown). The material of the developing roller 6 is not particularly limited, but a conductive elastic roller made of conductive urethane rubber or the like to which a conductive agent such as carbon black is added on the surface, a groove or sandblast treatment on the surface. It is possible to use a metal roller or a rubber or metal roller whose surface is coated with a resin.

  In the embodiment of the present invention, the surface of the developing roller 6 is sandblasted, and an aluminum developing roller having an average surface roughness Ra of 0.4 μm and a diameter of 16 mm and a length of 30 cm is used. The developing roller 6 carries a toner layer on its surface, is driven to rotate, and is an electrostatic latent image on the surface of the photosensitive drum 2 in an area where the developing roller 6 contacts the photosensitive drum 2 via the toner layer (hereinafter referred to as a developing area). The toner is supplied to the toner and developed to form a toner image.

  A motor driving means (not shown) is connected to the developing roller 6 and is rotationally driven by the driving means. The driving means is electrically connected to a power source and control means (not shown), and is driven to rotate by applying a voltage from the power source. The rotational driving force is transmitted to the developing roller 6 to rotate the developing roller 6.

  Further, the control means controls the voltage application to the driving means by the power source and the rotational driving of the developing roller 6. When toner is supplied to the electrostatic latent image from the developing roller 6 to the photosensitive drum 2, a developing bias voltage is applied to the developing roller 6 from a power source connected to the developing roller 6.

  The developing bias to be applied is about -200v to -1000v, and is set as needed according to the required image density. In this embodiment, development is performed at −300 v. The linear velocity of the developing roller 6 is 145 mm / sec.

  The supply roller 7 is a roller member that is provided so as to face the photosensitive drum 2 with the developing roller 6 interposed therebetween, and also serves as toner agitation, conveyance, and toner removal after development.

In this embodiment, the supply roller 7 is made of conductive urethane foam having a volume resistance of about 10 ⁵ Ωcm and a cell density of about 3 pieces / mm, has a diameter of 14 mm, a length of 30 cm, and a contact depth of 0 to the developing roller 6. .5 to 1 mm in contact.

  The supply roller 7 charges the toner accommodated in the internal space of the developing tank 5 by its driving rotation, and conveys the toner to the periphery of the developing roller 6. Further, the thickness of the toner layer on the surface of the developing roller 6 can be adjusted by controlling the rotation speed of the supply roller 7.

  The rotation speed of the supply roller 7 can be controlled by the control unit 201, and is usually a ratio of 0.7 to 1.2 with respect to the rotation speed of the developing roller 6. When the rotation speed of the supply roller 7 is less than 0.7 with respect to the rotation speed of the developing roller 6, the toner is not sufficiently conveyed to the developing roller 6, and an image defect due to insufficient image density or uneven conveyance occurs. .

  On the other hand, when the rotation speed of the supply roller 7 is 1.2 or more with respect to the rotation speed of the developing roller 6, the amount of toner transported to the developing roller 6 becomes excessive, and the toner layer regulation blade 9 has sufficient toner layer regulation. This is not performed, and image defects due to toner scattering occur as the toner charge amount decreases.

  In this embodiment, the linear velocity is 116 mm / sec. In addition, a bias of about −100 to −500 v can be applied in order to improve the toner transportability of the supply roller 7, but no bias is applied in the present embodiment.

  The agitating member 8 is a rotating member that is provided so as to face the developing roller 6 with the supply roller 7 interposed therebetween, and is rotated around an axis by a driving unit (not shown). The stirring member 8 uniformly mixes the toner stored in the developing tank 5 and the toner newly supplied from the toner cartridge (not shown) into the developing tank 5 via a toner hopper (not shown). Then, it is conveyed around the supply roller 7.

  The toner layer regulating blade 9 is a plate-like member extending in parallel to the axial direction of the developing roller 6 for regulating the amount of toner (toner layer thickness) to the developing roller 6. The toner layer regulating blade 9 includes a metal member 9a, a rubber member 9b, and a support member 10. Further, the toner layer regulating blade 9 is arranged in a cantilever shape in which one end in the short direction is supported by the support member 10 and the other end is extended toward the upstream side in the rotation direction R1 of the developing roller 6. The

  As an example, in the toner layer regulating blade 9 according to the present embodiment, the metal member 9a has dimensions of a width of 8 mm, a length of 30 cm, and a thickness of 0.1 mm, and is made of phosphor bronze. The rubber member 9b is made of urethane rubber having a thickness of 1.0 mm and a JIS-A hardness of 60 °. The metal member 9a and the rubber member 9b are fixed by welding or the like. Moreover, you may use conductive resin, stainless steel, etc. as a material of the metal members 9a.

The rubber member 9b and the developing roller 6 are pressurized at an applied pressure per unit length in the axial direction (hereinafter referred to as blade linear pressure) of 20 to 60 gf / cm. When the blade linear pressure is less than 20 gf / cm, the thickness of the toner layer on the developing roller 6 (toner layer thickness) is likely to cause uneven density due to non-uniformity. In this embodiment, the blade linear pressure is set to 35 gf / cm, and the toner amount on the developing roller 6 at this time is set to 0. Set in the range of 6-0.8 mg / cm ² . Further, the toner charge amount is −7 to −15 μC / g, and a bias having the same potential as the developing roller 6 is applied.

  Furthermore, in the present embodiment, when the toner layer is formed on the developing roller, the toner on the developing roller 6 after passing through the nip portion is deteriorated due to the decrease in toner fluidity and the formation of aggregates as the toner deteriorates. In order to prevent uneven toner amount and streak-like unevenness, the surface of the rubber member 9b in contact with the developing roller 6 is placed on the surface of the developing roller 6 with respect to the rotation direction R1 of the developing roller 6 as shown in FIG. The surface roughness of the surface of the rubber member 9b is changed from the center point K of the blade linear pressure of the layer regulating blade 9 toward the downstream side D from the upstream side U.

  In other words, the surface of the rubber member 9b in contact with the developing roller 6 is the center point K of the blade linear pressure of the toner layer regulating blade 9 (the point at which the blade linear pressure of the toner layer regulating blade 9 is the highest with respect to the developing roller 6). ), The upstream side U and the downstream side D have different surface roughnesses with respect to the rotation direction R1 of the developing roller 6. That is, the surface roughness on the downstream side D is formed to be smaller than the surface roughness on the upstream side U.

  More specifically, the surface (upstream contact surface) of the rubber member 9 b of the toner layer regulating blade 9 that contacts the developing roller 6 rotates from the center point K of the blade linear pressure of the toner layer regulating blade 9. The upstream side U is roughened in the direction R1. The surface of the rubber member 9b is roughened by a method of blasting non-metallic particles such as silica sand or metal particles at a high speed to roughen the surface (blasting). In this embodiment, the average surface roughness Ra is set to 0.05 to 0.4 μm, and the surface roughness gradually increases from the upstream side U to the center point K of the blade linear pressure with respect to the rotation direction R1 of the developing roller 6. A surface treatment is applied to reduce the size.

  As described above, the surface of the rubber member 9b of the toner layer regulating blade 9 that is in contact with the developing roller 6 is subjected to surface treatment, so that the toner in the region surrounded by the developing roller 6 and the upstream contact surface of the rubber member 9b. Therefore, it becomes possible to form a stable toner layer.

  Further, the surface roughness of the surface of the rubber member 9b gradually decreases toward the central point K of the blade linear pressure of the toner layer regulating blade 9, so that the toner layer is formed on the developing roller 6 before the toner layer is formed. The agglomerated toner can be pulverized.

  With such a configuration, the toner passing through the nip between the toner layer regulating blade 9 and the developing roller 6 can be made uniform when the toner layer is formed, and even with a low blade linear pressure of about 30 gf / cm. A toner layer can be formed.

  On the other hand, the surface of the rubber member 9b of the toner layer regulating blade 9 in contact with the developing roller 6 is downstream from the center point K of the blade linear pressure of the toner layer regulating blade 9 with respect to the rotation direction R1 of the developing roller 6. D performs mirror surface processing (mirror surface processing).

  Since the downstream side D is mirror-finished on the surface of the rubber member 9b, the surface of the toner can be made more uniform after the toner layer is formed on the developing roller.

  Further, on the downstream side D from the center point K of the blade linear pressure, the surface roughness of the mirror surface of the rubber member 9b is changed stepwise along the rotation direction R1 of the developing roller 6 to make the toner layer uniform. You may make it flexibly perform.

  As described above, the surface of the rubber member 9b in contact with the developing roller 6 is roughened with the upstream U from the center point K of the blade linear pressure of the toner layer regulating blade 9 with respect to the rotation direction R1 of the developing roller 6. In addition, by using the downstream D as a mirror surface and different surface roughness, it is possible to ensure toner transportability and make the toner layer formed on the developing roller 6 uniform. Further, even when the fluidity is lowered due to the deterioration of the toner and the toner aggregates are generated over a long period of time, a uniform toner layer can be formed on the developing roller, thereby providing a high-quality image. be able to.

DESCRIPTION OF SYMBOLS 1 Developing device 2 Photosensitive drum 5 Developing tank 6 Developing roller 7 Supply roller 8 Stirring member 9 Toner layer regulating blade 9a Metal member 9b Rubber member 10 Support member 100 Image forming apparatus 201, 211 Control unit 202 Storage unit 204 Display unit 205 Input unit 206 Communication unit 208 Image processing unit 209 Image forming unit 210 Fixing unit 207 Reading unit K Center point

Claims (3)

A developer carrier that is provided in an image forming apparatus used for image formation and supplies the developer to the electrostatic latent image formed on the electrostatic latent image carrier and develops it, and is carried on the surface of the developer carrier. A developer layer thickness regulating member that regulates the layer thickness of the developer, and developing the electrostatic latent image with the developer,
The developer layer thickness regulating member includes an elastic body that contacts the surface of the developer carrying body,
The developing device according to claim 1, wherein the surface of the elastic body changes in surface roughness from the upstream side to the downstream side with respect to the rotation direction of the developer carrier.   The developing device according to claim 1, wherein the surface roughness on the downstream side of the surface of the elastic body is smaller than the surface roughness on the upstream side.   The surface of the elastic body downstream from the central point of the blade linear pressure of the developer layer thickness regulating member with respect to the rotation direction of the developer carrier is a mirror surface, and the development from the central point of the blade linear pressure. The developing device according to claim 1, wherein the surface of the elastic body on the upstream side with respect to the rotation direction of the agent carrier is a rough surface.

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